On ploughs mounted on the three-point linkage there is generally a need to displace the working members themselves, that is to say the plough bodies with associated beams and so on, laterally relative to the tractor to achieve the correct distance between the inside of the tractor wheel that is rolling in the furrow behind the previous strip of inverted soil and the landside of the first plough body. The lateral adjustment is affected by both the track of the tractor, the tyre dimension of the tractor and the ploughing width of the plough. For a semi-mounted plough or a trailed plough, such lateral adjustment is desirable also because of the fact that there is a varying need with respect to where the tractor should be positioned relative to the edge of the unploughed field. The lateral adjustment is performed mechanically or hydraulically during ploughing, and it is typically effected by the frame of the plough being displaced laterally relative to the plough's tower or drawbar, to which the tractor is connected.
Many ploughs are equipped with devices for adjusting the ploughing width, that is to say the working width of each individual plough body. The applicant's own system is known under the names Van-Width® and Variomat®. When some versions of plough with such working-width adjustment are to be adjusted, the tractor driver must operate both the cylinder for working-width adjustment (to adjust the transverse spacing of the plough bodies) and the cylinder for displacing the plough laterally relative to the tower or the drawbar (to adjust the distance between the inside of the rear tractor wheel and the landside of the first plough body). This makes the working-width adjustment complicated, and there is a risk that the ploughing result will not be an optimum one, by the lateral displacement not giving the same ploughing width for the first plough body as for the subsequent ones.